Thor Forums

[FW28z]

One definite issue might be your batteries. When you put batteries in parallel, if they are not the same type/capacity and even age, you can have issues.

Typically the battery with the lower capacity (either due to AH rating or age) will charge first and can be seriously overcharged before the other two batteries reach their fully charged state. Since the batteries are all in parallel; with no isolation; and only a single charger, the charger cannot know that one battery is charged before the others. In fact the charger does not know you even have more than one battery.

This is why you should always change all of your batteries in a parallel configuration whenever you have a battery problem. The fact that you cooked one battery is evidence the batteries have different capacities.

Camping World should have told you they need to replace all three batteries.

And yes, you should disconnect either your converter's charger when using an inverter/charger or disable the charger function of the inverter. Chargers work by sensing the battery voltage. As the battery discharges, it's voltage will be lower, which causes the charger to raise it's voltage, resulting in a higher charge rate.

If you have two chargers connected to a battery, each charger will not be able to differentiate the battery voltage vs. the other charger's voltage (which will always be higher than the battery). Consequently, each charger will interpret the other charger's higher voltage as battery voltage, and drop it's voltage as it thinks the batteries are charged more than they are.

There is some hysteresis going on here between the two chargers, but at some point they will be in equilibrium at a lower voltage than needed to rapidly charge the battery. Depending on the design of the chargers, you may still get some charge; most likely a trickle charge; but the chargers output might take many hours to fully charge the batteries (if they even fully charge).

I would fix the problem by disconnecting/disabling one of the chargers and replacing all of the batteries at the same time with ones of the same model, brand, and age.